| Russian dandelion is a perennial herbaceous plant,which belongs to Taraxacum genus of Asteraceae family.It has important economic and scientific values,due to its roots containing 2.89?27.89%of rubber and 25?40%of inulin,as well as being taken as a model plant for studying mechanism of rubber synthesis.Because of its promising prospect of commercialization,three consortiums were established to speed up the process of commercialization and solve the issue,of which they can't produce natural rubber by themselves,in USA,Europe,and China,respectively.Taken K445,which is a better line of Russian dandelion,as the object,the paper has studied its technologies of propagation and culture,biomass estimation,and cultivation technology,the details as followed:1.Propagation and culture technologies:(1)Through orthogonal experimental design,we studied effects of concentration of KMnO4 solution,soaking time,and temperature on seed germination of Russian dandelion.It indicated that temperature is the key factor which affects seed germination,and discovered a new germination technology:seeds are soaked in 0.7%of KMnO4 solution for 2 h,then germinated under 23?.(2)With single-factor experiment,we studied impacts of sterilization time,types of hormone,and concentration on inducing rate and rooting rate of tissues of Russian dandelion,and established a highly efficient tissue culture and fast propagation system:leaves,as explants,are sterilized with 0.1%HgCl2,then put into culture medium with MS+2.0 mg·L-16-BA+1.0 mg·L-12,4-D to induce callus,then put into culture medium with 2.0 mg·L-16-BA+1.0 mg·L-12,4-D to induce dividing of adventitious buds,then put into culture medium with 2.0 mg·L-16-BA+1.0 mg·L-12,4-D.(3)On the basis of the successful tissue culture system,with single-factor experiment,we studied effects of different nutrition concentration,types of permeable compounds,and growth inhibitors on in-vitro conservation of germplasms of Russian dandelion,and established in-vitro conservation technology:put into 1/2 MS culture medium with 30 mg·L-1 of mannitol and 2.0 mg·L-1 of ABA,then the germplasms would be conserved as long as 10 months,with good growth afterwards.2.Cultivation technologies:(1)Using single-factor potted experiment with ANOVA and trend analysis,we studied impacts of different irrigation frequency on growth and yield of Russian dandelion,found that the best water concentration of soil is 28.0%,and the relationship between water concentration of soil and yield and yield constitutes of Russian dandelion is:when water concentration of the soil increases from 22.8%to 38.9%,the change trend of rubber yield fits cubic polynomial equation significantly,the change trend of total sugar concentration fits cubic polynomial equation significantly.(2)Through single-factor experiment with ANOVA and trend analysis,we studied impacts of nitrogen,phosphorus,and potassium as basal fertilizers on growth and yield of Russian dandelion,recommended the requirements of basal fertilizers for the local are:107.2 g·m-2 of urea,43.4 g·m-2 of ordinary superphosphate,10.5 g·m-2 of potassium chloride.We found that(A)the relationship between nitrogen basal fertilizer and yield and yield constitutes of Russian dandelion is:when adding nitrogen from 0 to 107.2 g·m-2,the change trend of rubber yield fits linear equation significantly,the change trend of total sugar yield fits linear equation significantly.(B)the relationship between phosphorus basal fertilizer and yield and yield constitutes of Russian dandelion is:when adding fertilizer from 0 to 10.5 g·m-2,the change trend of rubber yield fits linear equation significantly,the change trend of total sugar yield fits linear equation significantly.(C)the relationship between potassium basal fertilizer and yield and yield constitutes of Russian dandelion is:when adding fertilizer from 0 to 35.3 g·m-2 the change trend of rubber yield fits quadratic polynomial equation significantly,the change trend of total sugar yield fits linear equation significantly.(3)Through single-factor experiment with ANOVA and trend analysis,we studied effects of different plant densities on growth and yield of Russian dandelion.We recommended 20 X 20 cm as the best plant density to get a higher rubber yield,and found the relationship between plant density and yield and yield constitutes of Russian dandelion is:when plant density increases from 9.9 plants/m2 to 53.8 plants/m2,the change trend of rubber yield fits linear equation significantly,the change trend of total sugar yield fits linear equation significantly.(4)Through single-factor experiment with ANOVA and trend analysis,we studied effects of soil pH on growth and yield of Russian dandelion.We recommended 8.3 as the best soil pH to get a higher rubber yield,and found the relationship between soil pH and yield and yield constitutes of Russian dandelion is:when soil pH increases from 6.8 to 8.3,the change trend of rubber yield fits quadratic equation significantly,the change trend of total sugar yield fits linear equation significantly.3.Biomass estimation and cultivation technology optimization:(1)Estimation model of leaf biomass:through multiple stepwise linear regression method,we established estimation model of leaf biomass taking leaf length and width as variables:LB=11.8334.465*L+23.5*W+0.004*L*W+49.945*L0.5-115.611*W0.5+0.011*L2-0.219*W2,LB means leaf biomass(dry weight,mg),L means leaf length(mm),W means leaf width(mm),the model demands at least 15 leaves to have statistical significance.(2)Estimation model of root biomass:Using multiple regression method,we found the relationship between root biomass and root branches,stem diameter,leaf clusters,and leaf dry weight,and established estimation model of root biomass:RD=-0.902+1.316LD-2+0.139SD-0.049LN,RD means leaf biomass(dry weight,g),LD means leaf dry weight(g),LN means leaf clusters,SD means stem diameter(cm).(3)On the basis of previous single-factor experiments,using multiple linear regression method,we established optimized regression equations between leaf biomass,root biomass,rubber yield,and total sugar yield of Russian dandelion and available nitrogen,available phosphorus,available potassium,water content,plant density,and soil pH,respectively.Afterwards,we predicted that when soil water content is 28.0%,soil available nitrogen,phosphorus,and potassium are 160,82.4,and 302 mg·kg-1,plant density is 53.8 plants/m2,soil pH is 6.8,the leaf biomass of Russian dandelion gets the peak,namely 227.0 mg·kg-1;when soil water content is 28.0%,soil available nitrogen,phosphorus,and potassium are 328,87.8,and 357.2 mg·kg-1,plant density is 13.4 plants/m2,soil pH is 6.8,the root biomass is the highest,namely 221.0 mg·kg-1;when soil water content is 28.0%,soil available nitrogen,phosphorus,and potassium are 160,76.9,and 339 mg·kg-1,plant density is 13.4 plants/m2,soil pH is 6.8,the rubber yield gets the peak,namely 16.1 mg·kg-1;when soil water content is 28.0%,soil available nitrogen,phosphorus,and potassium are 160,76.9,and 339 mg·kg-1,plant density is 53.8 plants/m2,soil pH is 6.8,the total sugar yield gets the peak,namely 111.2 mg·kg-1. |
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